Add dynamic homepage study guidance

app/globals.css

@@ -157,6 +157,7 @@ h1{letter-spacing:-.04em;font-size:clamp(2rem,4vw,2.85rem)}
 .sync{border:1px solid #d8e5ff;box-shadow:0 8px 22px #bfdbfe88}
 .overview-link{box-shadow:0 6px 16px #dbeafe99;transition:.18s transform,.18s box-shadow}
 .overview-link:hover{transform:translateY(-1px);box-shadow:0 10px 22px #bfdbfe}
+.smart-tip{display:grid;grid-template-columns:190px minmax(0,1fr);gap:24px;align-items:center;margin:0 0 16px;padding:20px 22px;border:1px solid #cfe0ff;border-radius:20px;background:radial-gradient(circle at 92% 12%,#cfe2ff 0,transparent 26%),linear-gradient(120deg,#edf5ff,#fff 70%);box-shadow:0 12px 28px #dbeafe80}.smart-tip h2{margin:5px 0 0;font-size:1.25rem;letter-spacing:-.025em}.smart-tip>p{margin:0;color:#334155;font-size:1rem;line-height:1.75}
 .stats{gap:16px}
 .stat,.countdown{border-radius:20px;box-shadow:0 12px 28px #dbeafe80}
 .stat{border-color:#e0eaff;background:linear-gradient(145deg,#fff,#f9fbff)}